Mechanical tappet



y 1963 K. E. KUENY 3,089,473

MECHANICAL TAPPET Filed Feb. 1, 1962 IG- 9 56. /0 56M United States Patent Ofifice 3,089,473 Patented May 14, 1963 3,089,473 MECHANICAL TAPPET Kenneth E. Kueny, North Muslregon, Mich, assignor to Johnson Products, Inc., Muskegon, Mich., a corporation of Michigan Filed Feb. 1, 1962, Ser. No. 170,371 Claims. (Cl. 123-90) This invention relates to engine tappets and more particularly to lightweight mechanical tappets.

Continued development of internal combustion engines has resulted in shorter piston strokes with a markedly increased stroke rate. Overhead valve trains in such engines are consequently operated at a tremendously high rate of speed. To achieve the desired high stroke rate, the elements of the valve train must be light in weight to prevent lag due to inertia in the constantly reversing train. One relatively heavy component of the conventional valve trains is the tappet positioned to ride on one cam of the cam shaft. It operates the push rod which in turn actuates the rocker arm to the overhead valve.

Although it is conceivable that this heavy tappet could be lightened by shortening it, the adjacent push rod would then have to be lengthened to account for the difference. Lengthening of the push rod substantially lessens valve train rigidity-another essential characteristic of high speed valve trains. Conventional ways devised to accomplish lightening of the tappet have been to machine out the center of the tappet or to cast the tappet with a special coring to provide a hollow interior. Machining is costly, wasteful of material, time consuming and not fully effective without lessening the reliability of the tappet. Casting a hollow interior tappet is also relatively costly and cumbersome due to the delicate coring problems involved with the thousands of otherwise low cost tappet items.

It is an object of this invention to provide a mechanical tappet that comprises a remarkably lightweight structure for high speed engines, without necessitating tappet shortening, interior machining, or casting of hollow tappets with delicate interior cores.

Another object of this invention is to provide a tappet that is made lightweight, even though having the same or a greater length than conventional tappets. It possesses good alignment characteristics to prevent sloppy operation. It has excellent strength to withstand the constant pounding to which it is subjected over a long life period. It is relatively inexpensive to cast in spite of its unique configuration creating its lightweight characteristics.

These and other objects of this invention will be apparent upon studying the following specification in conjunction with the drawings in which:

FIG. 1 is a fragmentary elevational partially sectioned view of one form of the novel tappet installed in an internal combustion engine;

'FIG. 2 is a fragmentary sectional view of the novel tappet taken on plane IIII of the apparatus in FIG. 1;

FIG. 3 is an elevational fragmentary view of a second form of the novel tappet;

FIG. 4 is a sectional view of the second form. taken on plane IV--IV of FIG. 3;

FIG. 5 is an elevational fragmentary view of a third form of the novel tappet;

FIG. 6 is a sectional view taken on plane VI--VI of FIG. 5;

FIG. 7 is an elevational fragmentary view of a fourth form of the inventive tappet;

FIG. 8 is a sectional view taken on plane VIII-VIII of FIG. 7;

FIG. 9 is an elevational fragmentary view of a fifth form of the invention; and

FIG. 10 is a sectional view taken on plane XX of FIG. 9.

Basically, the inventive lightweight tappet comprises three spaced coaxial discs comprising the head, the central and the foot portions of the tappet, and integrally connecting pillars between the head and central portions and between the central and foot portions of the tappet respectively. The head and central portions each having a cylindrical periphery to maintain tappet alignment within the upper and lower portions of the tappet bore in the engine block. The pillars have a width substantially smaller than the diameter of the adjacent head, central or foot portion to prevent any contact of the. pillar with the corresponding portion of the engine tappet bore. The pillars are at least as long as and preferably are longer than the head, central and foot disc portions. The pillar between the central and foot portions preferably comprises panel ribbing, with the panels or legs radiating from the axis of the tappet to the tappet periphery, the optimum configuration being X-shaped.

Referring now to the drawings, the novel tappet 10 in the first form of the invention illustrated in FIG. 1 is shown installed in the block of an internal combustion engine 12. The engine includes cam shaft 14 with spaced cams 16 and 18 abutting the lower camming surfaces 20 of each tappet 10. The upper surface of each tappet includes a push rod seat 22 for receiving push rod 24. The push rod in turn abuts a rocker arm (not shown) actuating the overhead valve. The tappet fits slidably in an engine tappet bore 28 including an upper portion 30 and a lower portion 32 enclosing in intermediate lubricant reservoir or gallery 34. The tappet may be used with or without a hollow push rod lubricating system.

In order to achieve optimum high speed operation from the valve train, the novel tappet 10 is provided with an optimum lightweight construction without sacrificing required strength characteristics. This construction is achieved by casting the tappet into five integrally joined portions including head portion 40 having the push rod seat 22 therein, neck portion or column 42 with its substantially smaller cross section, central portion 44, second column 48, and foot portion 46 including the cam surface 20. It will be noted that central and foot discs or portions 44 and 46 are preferably substantially shorter in length than head portion 40 since the latter must possess suflicient length to retain its strength in spite of the recessed push rod seat therein. In the forms of the invention illustrated, the head, central, and foot portions all have the same diameter. However, the novel structure can also be used on a so-called mushroom tappet wherein the foot portion is of a slightly larger diameter than the central and head portions.

Pillar 48 in the optimum tappet possesses the lightest weight possible while still maintaining the required rigidity and strength needed for the high speed tappet. The preferred configuration for the pillar 48 is a ribbing having a cross-sectional configuration in the form of an X as shown in FIG. 2, ie the pillar comprises a plurality of rigid, integrally joined panels. Each of the four integral radially oriented legs of the X terminate at their outermost surfaces substantially radially inwardly of the cylindrical peripheries of central portion 44 and foot portion 46. It has been found that longer tappet and tappet bore life is obtained if no contact is permitted between the edges of column 48 and the tappet bore walls. The novel ribbing is readily formed by conventional casting techniques. The process is relatively inexpensive compared to prior unsatisfactory methods of internal machining and hollow casting processes. Further, neither the hardened push rod seat 22 nor the cam surface 20 j is affected by the external novel casting construction. These surfaces are critical to long tappet life.

Instead of the preferred X-shaped configuration as illustrated in FIGS. 1 and 2, the ribbing illustrated in FIGS. 3 and 4 may be utilized. This column 148 is composed of three integrally joined radially projecting legs connecting the foot portion 146 and the central portion 144 of the tappet 110. A cylindrical pillar or column may form the neck portion 142 between the head and the central portion of the tappet 110 as desired. Thus, the top of the tappet will appear as in FIG. 1 and FIG. 9. It will be obvious that the number of legs may be varied as desired.

In FIGS. 5, 6, 7, 8, 9 and 10 are shown three other forms which the novel tappet may assume. These are less preferred than those forms shown in FIGS. 1 and 2 or in FIGS. 3 and 4. The triangular shape of the column 248 of the tappet 210 in FIGS. 5 and 6, the circular cross-sectional configuration column 348 in tappet 310 in FIGS. 7 and 8, and the rectangular configuration of the pillar 443 in tappet 410 in FIGS. 9 and 10 constitute a heavier tappet construction than that shown in FIGS. 3 and 4. However, the novel structures illustrated in FIGS. 5 through 10 provide a lightweight yet sturdy tappet structure compared to conventional tappets and achieve high speed engine operation Without the inential lag characteristic of conventional tappets. The top of the tappets illustrated in FIGS. 5 and 7 may be like that shown in FIG. 9.

In the invention as illustrated, the neck pillar 42 is illustrated as a cylindrical column. This is advantageous when utilized with the lubricant flow system shown from reservoir 34 to the hollow push rod. However, within the broader scope of this invention, the neck pillar may also comprise a web-type construction. It is believed unnecessary to show further drawings of this since the sectional views would, for example, be exactly like those shown in FIGS. 2 and 4. This would still further reduce the tappet weight and inertial lag without sacrificing crucial strength characteristics.

Further obvious modifications in the forms of the invention illustrated may occur to those in the art upon studying the principles set forth in the foregoing specification. Thus, the invention is not to be limited to the forms illustrated, but only by the scope of the appended claims and the reasonably equivalent structures to those defined therein.

I claim:

1. A sturdy lightweight tappet having low inertial lag comprising: three spaced, coaxial, cylindrical discs comprising head, central and foot portions; rigid, integral pillars between said head and central portions and between said central and foot portions; said cylindrical head and central portions serving to align said tappet in the upper and lower portions of the engine tappet bore and prevent contact between said pillars and said bore; a cam contacting surface on said foot portion; and a push rod seat in said head portion.

2. A lightweight tappet comprising: a foot portion having an end camming face; a head portion spaced from said foot portion; said head portion having an end push rod seat, and having a cylindrical peripheral surface adapted to align the tappet in the upper portion of an engine tappet bore; a central portion spaced between said foot and head portions and having a cylindrical peripheral surface to align the tappet in the lower portion of an engine tappet bore; rigid integral pillars between said head and central portions and between said central and foot portions respectively, whereby said portions are structurally and functionally integrated into a lightweight tappet; said cylindrical head and central portions serving to align said tappet in the upper and lower portions of the engine tappet bore and prevent contact between said pillars and said bore.

3. A lightweight mechanical tappet comprising: a foot portion including an end cam face; a central alignment portion having a peripheral surface adapted to maintain the tappet aligned in the lower portion of an engine tappet bore; a head portion having an end push rod seat and a peripheral surface adapted to maintain the tappet aligned in the upper portion of an engine tappet bore; a neck between said head portion and said central portion having a smaller cross-sectional width than said head and central portions; and a portion between said central portion and said foot portion having a smaller cross-sectional width than said central and foot portions.

4. A lightweight tappet comprising: a cylindrical head portion; a reduced diameter rigid neck portion integral with said head portion; a cylindrical central body portion integral with said neck portion; and a foot portion integrally joined to said central portion by rigid integral ribbing panels having an overall width substantially less than the diameter of said foot portion.

5. The tappet in claim 4 wherein said ribbing has an X-shaped configuration.

References Cited in the file of this patent UNITED STATES PATENTS 2,324,006 Lenz et al July 13, 1943 2,493,783 Stanclitf Jan. 10, 1950 FOREIGN PATENTS 958,969 Germany Feb. 28, 1957 

3. A LIGHTWEIGHT MECHANICAL TAPPET COMPRISING: A FOOT PORTION INCLUDING AN END CAM FACE; A CENTRAL ALIGNMENT PORTION HAVING A PERIPHERAL SURFACE ADAPTED TO MAINTAIN THE TAPPET ALIGNED IN THE LOWER PORTION OF AN ENGINE TAPPET BORE; A HEAD PORTION HAVING AN END PUSH ROD SEAT AND A PERIPHERAL SURFACE ADAPTED TO MAINTAIN THE TAPPET ALIGNED IN THE UPPER PORTION OF AN ENGINE TAPET BORE; A NECK BETWEEN SAID HEAD PORTION OF AN ENGINE TAPPET BORE; A NECK A SMALLER CROSS-SECTIONAL WIDTH THAN SAID HEAD AND CENTRAL PORTIONS; AND A PORTION BETWEEN SAID CENTRAL PORTION AND SAID FOOT PORTION HAVING A SMALLER CROSS-SECTIONAL WIDTH THAN SAID CENTRAL AND FOOT PORTIONS. 